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I have a Harman Kardon audio system in my 2003 M3 convertible. My rear sub woofer (the one in the trunk between the rear seats) makes annoying rattles. I removed the rear seats to save weight on the car (about 40 lbs! less) so this may be part of the problem, but any recommendations on how to reduce the rattling? I covered where the seats used to be with black automotive carpeting. Maybe padding with dynamax between the carpet and the bare back (seat back rest) of the car would do the trick?

No help here, as mine rattles too. But, with the pass-through closed and the seat installed (so much more comfortable for rear passengers) the rattle stays in the trunk. Only good vibrations in the passenger compartment.

No help here, as mine rattles too. But, with the pass-through closed and the seat installed (so much more comfortable for rear passengers) the rattle stays in the trunk. Only good vibrations in the passenger compartment.

I'd like to add.... I dismounted the sub woofer from the car and left only the electrical connection. I played it and the same rattle is still there, it's not the trim or panels etc...., it's the actual sub woofer which is very disappointing.

To the subs defense, it could also be the signal from the amp or head unit (the radio unit in the front dash) which might be failing.

To troubleshoot the system, I've ordered a replacement head unit to try that first in case that is causing the crappy low frequency signal. If not, I'll try a replacement HK amp which sits in the rear left of the car (rear left passenger seating area). If that doesn't solve it, then I'll probably replace the HK amp with an Alpine 5 channel amp while keeping the head unit (and add a new Alpine sub woofer capable of 1000 Watts RMS for under $500 amp included (stock HK sub woofer is only 40 W!, can you imagine the difference?). If I still have the problem, I'll replace the head unit with an aftermarket one as well.

I hope it's either the head unit (Business CD edition, the typical kind) or the HK amp in the back, that would make things a lot easier. If not, HK sucks and I'll get rid of it...

Last edited by garrafa; 12-29-2012 at 07:51 PM.
Reason: rear right is wrong